Compact antennas with meandering shorting strip

Abstract

This thesis presents a number of small antenna designs by meandering short strip of each antenna. The first antenna design is the dual-band printed inverted-F antenna by meandering shorting strip. Conventional printed-IFA used the method like double stacked inverted-F or employs an L-shape strip which increases the antenna size and sensitive to the frequency. The proposed antenna is based on a simple printed-IFA, where the shorting strip is modified into a meandering shape such that the antenna can have double resonances. The first resonance is the fundamental resonance of the printed-IFA; while the additional operating band is achieved by the capacitive compensation of the higher resonance of the printed-IFA. As a result, the dual-band operation is obtained by the proposed antenna structure. The antenna finds an impedance bandwidths of 10.85% and 3.61% for S11<-10dB at 1.8 GHz and 2.4 GHz, respectively. The second antenna design by meandering shorting strip is the dual-band patch antenna by meandering shorting wall. By extending the width of the shorting strip, it comes to a shorting wall in the design. Conventional patch antenna achieves dual-frequency by cutting slot on the surface or adding a stacked patch. A novel technique that achieves dual-band by meandering shorting wall is proposed. By tactfully folding the shorting wall of the patch antenna, an additional well matched frequency band is obtained. The antenna finds the impedance bandwidths of 15.4% and 8% at 2.4 GHz and 3.3 GHz, respectively. Comprehensive studies on the meandered-shorting-wall patch antenna are provided. The final design is the wideband planar inverted-F antenna by meandering shorting strip. Conventional PIFA suffers single and narrow band with only 5-10% impedance bandwidth. A novel technique of meandering shorting strip is proposed to achieve a wideband PIFA. Different from the previous two antenna designs, the proposed PIFA can achieve wideband characteristic with the close up of the lower and upper frequency band. The antenna finds an impedance bandwidth of 45.2% for S11<-10dB from 1.565 to 2.48 GHz which can cover the GPS, DCS, IMT-2000, 2.4 GHz WLAN applications. Studies of the wideband PIFA including the frequency characteristics are provided.

Date of Award	2 Oct 2008
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Kai Ning Edward YUNG (Supervisor)